Magnesium Oxide Reaction cue cards

Magnesium + oxygen reaction

2Mg(s) + O₂(g) → 2MgO(s)

What reacts with magnesium to form magnesium oxide?

Oxygen (O₂)

Why does the mass increase when magnesium reacts with oxygen?

Oxygen is incorporated into the magnesium oxide product, adding the mass of oxygen to the original magnesium mass.

Why might the mass of magnesium oxide be higher than the original magnesium?

The original magnesium weighing only measured Mg, while the final product contains both Mg and O.

Evidence that a new compound formed

The product changed colour and texture; magnesium was ductile and malleable, while magnesium oxide was very brittle.

Why is magnesium oxide a new compound?

Its properties are different from the original magnesium and oxygen, showing that a new substance with different properties formed.

Balanced equation for magnesium reacting with oxygen

2Mg(s) + O₂(g) → 2MgO(s)

Why are there 2 Mg atoms in the magnesium oxide equation?

Oxygen exists as O₂, so two Mg atoms are needed to form two MgO units and conserve atoms.

Mass of 1 mol Mg

Approximately 24 g

Mass of 1 mol O₂

Approximately 32 g

Mass of 2 mol Mg

Approximately 48 g

Mass of 2 mol MgO

Approximately 80 g

If magnesium only reacted with one oxygen atom, would the mass still double?

No. The amount of oxygen incorporated would be different, so the product mass would not simply double.

Ionic compound

A compound made of positive and negative ions held together by electrostatic attraction.

Ions in magnesium oxide

Mg²⁺ and O²⁻

Why are Mg²⁺ and O²⁻ attracted to each other?

Oppositely charged ions attract through electrostatic forces.

Why should the lid of the crucible be slightly lifted during the magnesium reaction?

To allow oxygen into the crucible so the reaction can continue while limiting the loss of solid magnesium oxide.

Why shouldn't the lid be completely removed?

More heat would be lost, lowering the temperature and slowing the reaction.

Effect of lower temperature on particle movement

Particles have less kinetic energy and move more slowly, causing fewer frequent collisions.

Effect of lower temperature on successful collisions

A smaller proportion of particles have enough energy for collisions to be successful.

Aluminium + oxygen word equation

Aluminium + oxygen → aluminium oxide

Balanced aluminium oxide equation

4Al(s) + 3O₂(g) → 2Al₂O₃(s)

Simplified aluminium oxide equation

2Al(s) + 3/2O₂(g) → Al₂O₃(s)

Why can coefficients be multiplied by 2 in a chemical equation?

Multiplying every coefficient by the same number gives an equivalent balanced equation while maintaining the same ratio of particles or moles.

How do you know a chemical equation is balanced?

The number of atoms of each element must be the same on both sides of the equation.

Why must chemical equations be balanced?

Atoms are conserved during chemical reactions; they are rearranged but not created or destroyed.